Field of the Invention
The invention relates to an integrated radiofrequency circuit component having a resonant circuit with a capacitor whose value can be set for a predetermined frequency range by a tuning diode.
To date, integrated components have not been used for resonant circuits or signal generators in the frequency range from 1.5 to 3 gigahertz. At the present time, either discrete coils and variable-capacitance diodes are employed or modules including a plurality of integrated components in a housing are used.
However, there is a need for integrated components with resonant circuits or signal generators. In particular, tunable, voltage-controlled integrated components are required. The customary circuits for voltage-controlled resonant circuits contain at least one tuning diode at which a DC voltage is present as bias voltage and is connected with a polarity opposite to the forward direction. The junction capacitance of the tuning diode is then a monotonic function of the bias voltage. The resonant circuit is therefore provided with a voltage-regulated capacitance that can be used to set the resonant frequency of the resonant circuit. In this case, the bias voltage serves for traversing the frequency band that can be utilized.
The specification of a finished integrated component having a resonant circuit also has a defined relationship between the bias voltage and the resonant frequency. However, since the electrical properties of all of the circuit elements can fluctuate in a tolerance range, the possibility for trimming the resonant frequency of the resonant circuit must exist.
From the book “Microwave and Wireless Synthesizers” by Ulrich L. Rohde, New York 1997, pages 62 and 63, it is known to perform the fine control of a resonant circuit by using a tuning diode at which a DC voltage is present as a bias voltage and is connected with a polarity opposite to the forward direction. Provided in parallel with the tuning diode are second and third tuning diodes that are connected with a polarity in opposition to one another and between which, a DC voltage is present as a bias voltage. In this manner, coarse control of the resonant frequency of the resonant circuit can be performed.